An example of an article transport facility including a plurality of article transport vehicles (3) which travel along a track (2) to transfer articles at a plurality of article transfer locations is disclosed in JP No. 4232112 B2. Note that the reference numerals in parentheses in the present BACKGROUND ART section are those used in this reference. The track (2) of the article transport facility of the example in this reference is linear, and is of a type with two ends including one end and an opposite end. In addition, two article transport vehicles (3) are provided (3a, 3b). One ground side controller (14) which controls the traveling of the two article transport vehicles (3 (3a, 3b)) is provided in the article transport facility. The ground side controller (14) and each article transport vehicle (3 (3a, 3b)) communicate with each other using an optical transmission device (16, 17). Provided at each end of the track (2) is an optical position detecting sensor (15) for detecting the positions of article transport vehicles (3 (3a, 3b)) along the track (2) by measuring the distance between each end of the track and the article transport vehicle (3) that is closer to that end. The detection information from the position detecting sensors (15) is inputted into the ground side controller (14). The ground side controller (14) manages the operations of the article transport vehicles (3 (3a, 3b)) on the track (2) based on the detection information from the position detecting sensors (15).
Thus, when the track (2) is linear in shape, the ground side controller (14) can control the article transport vehicles (3) such that they do not come into contact with each other, based on the position of each article transport vehicle (3) detected by the detection sensor (15) provided at each end portion of the track (2). However, when the track (2) is curved, there is a blind spot in the detection area of a position detecting sensor (15); thus, providing a position detecting sensor (15) only at each end is insufficient to perform a proper control. JP4340976 B2 discloses an article transport facility in which the track (K) along which article transport vehicles (3) travel has a curved portion. The track (K) consists of two straight sections (L1, L2), and a curved section (R) located between the two straight sections (L1, L2). In this article transport facility, optical position detecting sensors (15) are located at both ends and at outward locations of the curved section of the track (K) to detect the positions of the article transport vehicles (3) in each straight section (L1, L2) and in areas partially including the curved section (R). Further, the article transport vehicles (3) are prevented from coming into contact with each other by controlling the article transport vehicles (3) such that only one is exclusively allowed to enter the curved section (R).